Generators are found in virtually every motor vehicle manufactured today. These generators, such as the common Lundell generator, produce alternating current to meet the vehicle's electrical needs. While the engine of the vehicle is running, the generator produces sufficient electricity to supply the vehicle's electrical demands and to recharge the battery.
An important component of the generator is the stator. In most generators, the stator contains the main current-carrying winding in which electromotive force produced by magnetic flux is induced. Typically, the current-carrying winding consists of conducting wire, which is wound and inserted into the slots of the stator. Each slot is located between two teeth. The wire is wound and inserted into slots in the stator in bundles. The prior art teaches the winding and insertion of wire having a rounded profile. This rounded wire, however, has several disadvantages associated with its use in a conventional stator.
First, the bundles of rounded wire do not occupy the stator slots in an efficient manner. Typically, the ratio of copper wire area to total slot area is 50%. This conventional design produces a lower output current and is less efficient electrically than a design in which the wire occupies a higher ratio of the slot.
Second, in a conventional stator design, two features are used to retain the wire in the slot: tooth tips and wedges. The teeth of the conventional stator are widened at the bottom of the slot to make the slot correspondingly narrower. In addition, a paper wedge typically is inserted into the slot after the bundle of wire has been inserted. Insertion of the wedge is a significant problem in the manufacturing area, and the process of insertion raises cost by increasing equipment down time and maintenance.
Third, the conventional stator design does not permit efficient stamping of the stator core. The stamping of a conventional stator core lamination according to the prior art produces a significant amount of scrap. This low material utilization results because the conventional stator design uses widened tooth tips.
Fourth, the use of rounded wire in the conventional stator design results in poor heat conduction because the wire is loosely bundled in the slot. This poor heat conduction results in higher stator wire temperatures. In turn, this higher temperature decreases the reliability, performance, and efficiency of the wire.